IMPROVEMENTS RELATING TO PATIENT HOISTS

Abstract: A patient hoist has parallel legs which can be splayed by a lever mechanism (50) which is swung about axis (52) by a pedal (not seen in this view) which is generally parallel to the beam (10) on which the legs are pivoted, and which pedal is rocked about an axis lying parallel to and between the legs so that a pin (46) depending from the pedal moves in an arc lying in a vertical plane to cause that swinging movement.

Description: IMPROVEMENTS RELATING TO PATIENT HOISTS A well known kind of hoist, to which this invention relates, has a transverse beam carrying a mast which supports a jib for suspending the patient. The beam is carried on a pair of legs which are pivoted to the beam, and there are castors on the ends of the beam and legs. The legs are connected to a lever by tie rods, and the lever can be swung to displace the legs between one extreme position in which they are close and parallel, for example for manoeuvreing the hoist along passageways, through doors etc., and a maximum splayed position when they may for example diverge about a wheelchair. The positions may be indexed, that is detent engaged, and there may be intermediate positions. The current industry standard arrangement for moving the legs includes a lever upstanding from the beam and generally parallel to the mast, engaged midway along its length in a gate acting as the detent mechanism, and coupled at its lower end for displacing the legs between the various positions. The arrangement described has a number of disadvantages namely:- The force required to re-position the legs of a patient hoist when bearing a patient is considerable. This difficulty is further exacerbated when the free movement of castors attached to the under carriage is inhibited by a resistive floor surface such as a carpet. The translational/rotational force thus required can be considerable. The vertical lever used as the positioning handle can frequently become entangled with other parts of the mechanism such as the various cords which form a part of electrically operated hoists. This can interfere with the smooth operation of the hoist and deflect the attention of the operator away from the patient. Also, the lever used in the mechanism extends from the struts at the base generally to the waist level of the operator. The length of the lever required imposes a considerable force on the linkage points at the base of the lever. The force involved can lead to physical strain on the components involved and eventual mechanical failure of the parts. The object of the invention is to provide improvements. According to the invention, a pedal is mounted on an axis generally parallel to the lengths of the legs and is rockable about that axis, and the pedal is connected to the legs to displace them. The pedal can be, and is indeed meant to be, foot operated. This enables the user to apply appropriate force for example by applying his/her weight to the pedal without it being necessary to relinquish the steering handles. The conversion of the generally vertically directed force from the downward movement of the foot pedal to the oppositely directed horizontal forces needed to splay or converge the legs may be accomplished by providing the pedal with a pin which is normal to the length of the pedal and which is arranged to swing arcuately so that the path of the pin lies in a vertical plane, when the pedal is rocked. The lower end of the pin may engage in a clevis fork provided on the lever which is coupled to the tie rods. To accommodate for the movement of the end of the rod relative to a horizontal plane due to its arcuate travel, the lever which is coupled to the tie rods may be arranged so as to be pivotable simultaneously about two axes namely a first vertical pivotal axis so as to displace opposite ends of the lever in opposite directions and displace the tie rods correspondingly, and at the same time pivot in a vertical plane about one end of the lever when the other end follows the movement of the pin end. This may be facilitated by making the connection between the lever and the vertical axis one where the lever is spring urged to a horizontal plane but can be displaced out of that plane during its pivotal movements. Conveniently the lever is provided with an indexing detent which is lifted out of engagement at the commencement of a leg adjustment and is spring returned at the completion of the adjustment. The invention is now more particularly described with reference to the accompanying drawings wherein:- Figure 1 is a perspective view showing a typical hoist according to the prior art; Figure 2 is a fragmentary rear elevation of a similar hoist but provided with the features of the present invention; Figure 3 is a fragmentary top plan view of the arrangement of Figure 2; Figure A is a fragmentary underneath plan view of the arrangement of Figure 2; and Figure 5 is a fragmentary side elevation of the same on a larger scale, showing parts in a position occupied when a leg adjustment is being effected. Referring first to Figure 1, the typical hoist comprises a transverse beam 10 which pivotally supports a pair of legs 12 14 which are shown in full lines in a parallel position and in dotted lines in a first diverging position. The legs have castors 11 at their ends, and so does the beam. The beam supports a mast 16, a pivoted jib boom 18, and a strut mechanism 20 for lifting and lowering the boom and any load such as a patient who may be seated on a structure suspended from the hooks 22. In this prior arrangement of Figure 1, the legs 12 14 are closed together to the parallel position, spread to the diverged position, and possibly spread to an even greater diverging position by means of a pair of tie rods 26 28 individually pinned to the legs, and coupled to opposite ends of a lever 30 which is pivoted between its ends on a vertical axis, and a vertically extending handle 32 is moved from side-to-side to displace that lever 30 about its pivot. A gate 34 is provided to engage the handle in any one of the predetermined positions. Turning now to Figures 2 to 5 illustrating the present invention, which is applied to a hoist of the same general kind comprising beam, legs and mast. In this case, the beam is provided with a journal boss 30 (Fig.5) supporting a pedal shaft 31 which extends in a horizontal plane parallel to and midway between the legs 12 14 when they are parallel. The pedal shaft is fixed to the pedal structure (see Figure 3), which comprises an elongated plate 36 extending generally parallel to the beam as seen in plan view and conveniently provided with pedal rubbers 38 38 for non-slip contact by a user's foot at each end of the part 36. This plate 36 is located generally parallel to a tubular member 40 which may be a square section tube, seen end on in Figure 5. Strut 42 is located in and extends along the tube 40 and is connected to the individual pedals by rods 43 45 which extend through apertures in the wall of the tube 40 for this purpose. The strut 42 is provide centrally of its length with a drive pin 44 slidable in a guide boss 46 fixed to the lower face of the tube 40, that is the face opposite to that adjacent to the pedal structure 36 38. The pin has a reduced diameter end portion 46 which, in Figures 2 and 5 is seen to be engaged in one end of operating lever 50. As best seen in Figure 4, the lever 50 is pivoted between its ends about the axis 52 and the pivot pin has a head 54 (Figure 5) which traps a helical spring 56 between the head and the lever. This normally urges the lever to lie parallel and flat against index plate 60 which is fixed to the underside of the transverse member 10 e.g. by bolts or welding not shown. Figure 5 illustrates a packing piece 62 located between the member 10 and the plate 60, but the presence or absence of such packing piece depends upon the dimensions of the other parts. The index plate 60 is provided with an arcuate row of index holes 66, and the lever 50 is provided with a detent 68 for engagement in any one of those holes depending upon the position of the parts. Figure 5 shows the detent disengaged from the hole due to the lever 50 being tilted against the spring, as more particularly explained hereinafter. The lever 50 is connected to the respective legs 12 14 by coupling rods 70 72 which may be screw connected so as to be adjustable in length and have clevis forks at each end to allow tilting e.g. in movement of the lever to the Figure 5 position. The pivot points between the legs and the transverse member 10 are indicated by the reference numerals 74, being disposed in projections from the beam. When the legs are parallel, the lever 52 will be in one extreme angular position about pivot 52 and detent 68 will be engaged in one of the holes 66 at a one end of the row of holes. In order to diverge the legs, the uppermost of the pedals namely 38A Figure 2, is depressed and this displaces the strut 42 within the tubular member 40 and moves the pin 46 axially. The end of the pin is engaged in a clevis fork 78 in the extreme end of the lever 50, and consequently this pedal displacement tilts the lever 50 so as to fulcrum about its extreme end 80, i.e. the end opposite to the clevis, thereby compressing the spring 56 and at the same time taking the detent pin 68 out of its detent hole 66. The displacing force also rocks the pedal about the pedal shaft journalled in the part 30 i.e. in the direction of the arrow A Figure 2 and this causes the bottom end portion 46 of the pin to move in an arc. Since the pin is engaged in the clevis fork this also serves to pivot the lever 50 about the pin 52, i.e. turn the lever angularly, and the tie rods 72 then displace the legs. With a suitable spring, the action is such as to take the detent 68 from one recess 66 to the next, and in effect index the legs from the parallel position to a first diverged position. In that position, the pedal structure may be generally horizontal i.e. parallel to the transverse member 10 when viewed in the Figure 2 position. A repeat operation depressing the pedal 38A will result in it becoming inclined oppositely to the position seen in Figure 2 and the legs being further diverged. From the first or second diverged position, the legs may be returned towards or to the parallel position by an almost exactly similar operation but depressing the opposite one of the pedals, resulting in the same pivotal action of the lever 50 about end 80, but opposite angular movement of the lever 50 about the pivot axis 52. The spring is also effective to return the strut 42 and plate 36 to the illustrated positions relative to the tube. It will be appreciated that Figure 5 shows the pedal in the foot depressed position i.e. part-way through a leg adjustment operation.

Claims: CLAIMS 1. A hoist of the kind comprising a mast supported by a transverse beam, a pair of legs pivoted to the beam, coupling rods connecting the legs to spaced points of a lever, and means for pivoting the lever so as to displace the legs between a first position in which the legs are generally parallel and at least one other position in which the legs are splayed, characterised in that a pedal is mounted on an axis generally parallel to the length of the legs and is rockable about that axis, the pedal being connected to said lever. 2. A hoist as claimed in Claim 1 wherein said lever is provided with a clevis fork engaged by a drive pin carried by said pedal, the drive pin being moved angularly about the pedal axis when the pedal is rocked and serving to displace the lever about an axis perpendicular to the pedal axis. 3. A hoist as claimed in Claim 2 wherein said lever is adapted and arranged to be pivotable about said perpendicular axis and also about a fulcrum located at one end of the lever for moving in an arc lying in a plane containing said perpendicular axis. 4. A hoist as claimed in Claim 3 wherein the lever is pivoted on a headed pin and spring means urge the lever to a position normal to said perpendicular axis. 5. A hoist as claimed in any preceding claim comprising detent means for indexing the legs in any of a plurality of predetermined positions. 6. A hoist as claimed in at least Claims 3 and 5 wherein the lever is provided with a detent and is pivoted relative to a detent plate provided with a row of recesses for selective engagement with the detent according to its position. 7. A hoist as claimed in any preceding claim wherein said pedal is arranged to be inclined to an extreme position wherein the legs are parallel and an opposite extreme position wherein the legs are splayed to a maximum extent. 8. A hoist as claimed in at least Claim 4 wherein the pedal comprises first and second parts which are relatively displaceable, and the second part is coupled to said drive pin which is engaged with the clevis fork, and the spring which urges the lever also serves to return the first and second parts to a start position after a leg adjustment operation. 9. A hoist substantially as described with reference to Figures 2-5 of the accompanying drawings.

Inventors: HENRY MICHAEL CHRISTOPHER, HENRY, MICHAEL, CHRISTOPHER
Applicants: HENRY MICHAEL CHRISTOPHER, HUNTLEIGH TECHNOLOGY PLC, HENRY, MICHAEL, CHRISTOPHER
Application year: 1994
Main classification: A61G7
IPC codes: A61G7